Helicopter



' May 2, 1939.

G. DE BOTHEZAT 2,156,334

HELICOPTER Filed Dec.. :50, 1937 ,5 Shets-Sheet 1 Ma 2,1939. 1 5E B THEZ2,156,334

HELICOPTER 5 Sheets-Sheet 2 Filed De c. 30, 19:57

ATTORNEY- May 2-, 1939;

' G.DE BOTHEZAT v 2,156,334

' HELICOPTER Filed Dec. 50, 1957 5 Sheets-Sheet 5 lNV TOR A ORNEYS y 2,1939- G.'DE BOTHEZAT 2,156,334

I HELICOPTER File d Dec. 50, 1937 s Sheets-Sheet 4 lNVE TO May 2,1939.c. DEBOTHEZAT 2,156,334 I HELICOPTER F-il ed Dec. 30, 1957 s Sheets-Sheet 5v \J Ai'TORNEY Patented May g UNITED Sm...

PA E T oFFiCn- George de Bothelat, New York, N. Y.,.asaignor to-Helicopt'cr Corporation of America, Long City, N. Y a corporation ofNew York Application member-- so. 1931, Serial m. 12am GCiahm. (omen-1v)This invention relates to aircraft of the helicopier type andparticularly to a construction insuring the inherent stability of suchapparatus.

" The object of the invention is to provide a helicopter which will beself-adjusting to maintain the proper operative and stable relationbetween the lifting unit and the loaded part.

A further object of the invention is to provide a helicopter which whileusing airscrews pivotally suspended at their hubs will be fullyeffective to maintain stability of the craft as a whole.

A further object of the invention particularlyin the division ofthehelicopter into relative pivo ted parts will appear from the followingdescription taken in connection with the following drawin'gs, in whichFigs. 1 2 and 3 are diagrammatic elevational views illustrating theinvention and shdzwing diii'erent relations between the partsof thelreligo copter Fig. 9 isa sectional view illustrating a modified trackand roller construction; 7 Fig. 10 is a diagrammatic perspective viewillustrating a modified system of connectionbetween the upper and lowerpartsof the helicopter: ,Fig. 11 is an elevational view of a modifiedform of helicopter; Fig. 12 is an enlarged diagrammatic viewillustrating the relations of the parts of the helicopter shown-inFlg.1-1; Fig. 13 is a diagrammatic view showing differentrelativepositions of the upper part of the 45 helicopter; Y

Fig. 14 is a partial elevational diagrammatic view showing a system ofcontrol of the tilting of the upper part of the helicopter with relationto the lower part; 50 Fig. 15 is a partial elevational diagrammaticview. showing the tilting oi the upper part of the helicopter withrelation to the lower part;

Fig. 16 is a diagrammatic elevational view showing the helicopterprovided with control fins 5 located in and out of the slip stream;

. generate any substantial restoring torque or moments.

stream but rotating in opposite directions, for

Figs. 17 and 18 are diagrammatic crosssectional views illustrating theoperation of the slip stream'flns; and I t Fig. 19 is a diagrammaticview illustrating amodified method of controlling the tipping of theupper part of the helicopter withvrelation to the lower part.

It has been demonstrated that there is great advantage in having theblades oflarg air screws suspended pivotally at their hubs, i. e.. 10

connected to the hubs through universal joints or equivalentarrangements, air screws so mounted being almost entirely'relieved ofbending and subject mostly to tension alone. A helicopter using suchsuspended blades could not be rendered 16 inherently stable by anyaerodynamical forces emanating from the air screws because thesuspension of the blades precludes the possibility of developing anysubstantial aero-dynamical moments and transmitting these to the body ofgo the helicopter. Air screws with hinged or suspended blades arerelatively insensible to air dis- I turbances insofar as the productionof aero-dynamical moments in relation to the axis of their rotation isconcerned, because such disturbances produce chiefly an oscillation ofthe blades around their hinges and are therefore practically nottransmitted further.

As a direct result such air screws are unable to The present method oiinsuring stability of the I helicopter is specially intended'for usewith pairs of .air screws where one propeller or air screw is disposedright under the other in the same slip instance as shown in applicantscopending application-Serial No.-92,307. v f

It is apparent that if such a pair of-air screws together with theengine operating them is attached in suspended relation to the body ofthe flying machine (the fuselage containing the pilot and passengerswith the landing gear) 'at a point above the centers of gravity of both,the air screwengine set'and the helicopter body'with such system wouldbe inherently stable.

Referring for example to the helicopterschematicallyrepresented in Fig.l, S represents the two air screws and the engine driving them and withthe gasollnetank located directly underneath, and it is presupposed thatthis unit is in some way suspended at 0 through a connection permittingoscillation ofthe unit S in all directions. It. is also assumed that thebody B of the helicopter is independently rigidly connected to a thiscenter of oscillation O. The whole system then takes the form of twopendulurns, the S unit being the shorter one with its center of gravityat 91 and the other, the longer one, comprising the helicopter body Bwith its center of gravity at 92. Both able to oscillate around thecenter 0 the period of oscillation 01' unit S is naturally shorter thanthat of the unit B because the length l1(0'g1) is substantially lessthan the length 12(092).

If such a system gets an inclination either longitudinal or lateral, theresult may be considered under three conditions:

1. Ii the body B swings out of position (see Fig. 2) -then the thrust Qof the upper unit S will prevent the point of suspension 0 developingany substantial downward acceleration and the weight in of the body Bwill swing it back into position.

2. If unit S swings out oi position then its weight n will produce therestoring action (see Fig. 3). It should be noted that disturbances ofunit S will occur rather seldom because of the use of the suspended typeof propeller blades.

3. If both units S and B simultaneously take the same deviation from thevertical then the unit S having a shorter period of oscillation will bethe first to swing out 01' the center line O g1 g2, and thereafter theflying machine will be found substantially in the conditions of case 1.Of course, sufiicient damping must be provided on the relative movementeven when the helicopter is hovering in order that no mutualamplification of the oscillations may develop.

A method of securing the suspension of the unit S above its center ofgravity would be todrive both propellers by an engine locatedsufiiciently below the propeller so as to obtain'the relation represenedin Fig. 4 where E is the engine with the gasolene tank below suspendedby a universal joint 0' to the body B and driving a system of propellersor air screws through a gear drive D located between the air screws (asillustrated for instance in applicant's copendlng application Serial No.182,400) This would require a rather long connecting member (see Fig. 4)between the engine and the air screws in order to get the desired valuesof the lengths l1 (0 g1) and l2 (0 m) for reliable inherent stability.

Another method is to connect units S and B so that their relativemotions are as though they were rotating around a common center 0. In

such case any point of unit' S or unit B describes a line on a spherehaving 0 as a center when units S and B oscillate around the pointO.Thus it is sumcient to connect units S and B by an intermediary of asliding spherical fit as illustrated in Fig. 5, in order to attain therotation of both units S and B around the center of oscillation 0. Suchspherical joint may for example consist of a spherical disk 6 rigidlyconnected to the body B and sliding easily within a spherical casing crigidly connected to units and opened at the bottom for the suspendingconnection to the disk cl. Such connection of units S and B permits thelengths l1 and 12 to be given any required values and permits the engineto be located between the air screws so that very light types of drivingmeans for the air screws may be adopted.

This arrangement of Fig. 5 also permits the torques oi the air screws tobe self-balancing when slight differences between the two oppositetorques occur, the lifting unit S being free to rotate around thevertical axis. It has the disadvantage oi. requiring an engine theoperation of which is not. afiected by slight rotation and in additionfurther complicates the installation of the controls betweenthe-relatively rotating set S and the body B of the helicopter, therotation of which i prevented'by vertical fins attached to the body andappropriately disposed in the slip stream from the air-screws.

To permit relative tipping oi the helicopter parts without relativerotation, the units S and B may be connected by a system of cylindricaltrackways and rollers illustrated inFig. 6. In this system the trackways2|, 22 are cylindrical around an axis through the center of oscillationO and are connected rigidly to the helicopter body B. The trackways 23,24 are also cylindrical around an axis through the center of oscillation0 and at right angles to the cylindrical axis of trackways 2i, 22, thetrackways 23, 24 being rigidly connected to the upper unit S. Thetrack'- ways are connected by a frame or carriage F through the mediumof eight rollers in two sets. The rollers 25, 26 of one set run intrackways 2i, 22 respectively and the rollers 21, 28 of the other setrun in trackways 23, 24 respectively, all of these rollers beingrotatably connected to the frame F as indicated diagrammatically in Fig.6. A typical roller is shown in Fig. 'l with the trackway constructionindicated in Fig. 8, and an alternative roller and track in Fig. 9 wherethe channel 2! has overhanging edges trapping the roller 25, which isprovided at its end with the ball caster 29. This system of connectionprovides two cylindrical surfaces with mutually perpendicular axespassing through the center of rotation 0, one of the axes preferablybeing perpendicular to the plane of symmetry of the helicopter and theother disposed in the plane of symmetry. It is not necessary that thetwo I axes precisely pass through and intersect at the center 0. Thecarriage or frame F therefore freely rolls in both lateral andlongitudinal direction. There is, of course, a small clearance betweenthe rollers and the rails or tracks, and when the air screws are notlifting then the rollers bear upon the lower rails or tracks 2|, 22 andon the upper rails or tracks 23, 24. In flight the rollers bear upon theupper tracks M, 22, and upon the lower tracks 23, 24. It is quiteevident that such rail and carriage system located between the airscrew-engine set S in the body of the helicopter body B is as torelative movement equivalent to their pivotal connection at the centerof oscillation 0 located above their centers of gravity.

Instead of having the rails attached to the upper unit S and the bodyunit B the rollers may be connected to these units and the intermediateframe or carriage formed by a double system of tracks or rails connectedto be engaged by the rollers as shown in Fig. 10. Here the upper unit Sis connected through frame holding its gas tank T to sets of rollers 33,36 mounted on the lower part of the tank while the lower body B isconnected through suspension members F1; to sets of rollers 3i, 32. Theintermediate frame F comprises the longitudinal rails or trackways 37,38 circling around the oscillation O, and the transverse trackways 35,36 also circle around this same center, the two trackways beingconnected together in a single frame F". The rollers 30, connected tothe helicopter body B run in the trackways 35, 36 respectively while therollers 33, 3% of the unit S run in trackways 37, 38 respectively. i

amass;

With this system of helicopter will appear as schematically representedin Fig. ll where E is the engine operatingthe two air screws in oppositedirections, T is the gasolene tank and II are hydraulic dampers at theends of the trackways. these dampers being of any conventional typeinstalled in the both longitudinal and lateral rails and limiting theoscillations to aperiodic or substantially aperiodic oscillations. Anyattachments of the air screw-engine unit to the body of the helicopterbody B as shown in Figs. 5, 6, and 11 may be called a high-centersuspension insuring a complete inherent stability of the helicopter andalso advantageous in connection with other features of helicopteroperation.

In order to secure a forward motion of the helicopter, it is suili'eientto tilt the thrust line preserving completeinherent stability in forwardcan be attained as illustrated in Fig. 12. The air screw-engine set S inaddition to being oscillatable around the center 0. which will be calledthe-dynamical center because the system freely oscillates around thiscenter, is also made movable around the axis C, located above all andwhich will be called the static axis. This axis 0 is perpendiculan tothe plane of symmetry. of the helicopter. The unit S is only displacedin the $0 longitudinal sense around this axis and is automaticallylocked in diiierent positions after heing set under the desiredinclination.

This may be attained, for example, by sliding the air screw engine set Slongitudinally along a cylindrical surface Having C as an axis, thissurface being in the form of curved rails, such as 42, 43 (see Fig. 12)rigidly attached to the top of a carriage 4| carried by-the rollers 33of the system of the previously described rolling rails.

It can be readily shown that the statical axis C can be taken at suchdistance above the dynamical center '0 that the moment of the air screwthrust Q'and the weight in of the'unit S will both balance (for a givenvalue Q) in relation to the dynamical center O. for any angle ofdisplacement of the set S along'the guides 42.

53. This means that if the'air screw set S is tipped by a given anglearound the center 0 and locked in such adjusted position, the wholesystem will remain in equilibrium in relation to the dynamical center 0as was previously the case when.

the thrust Q was truly vertical. Only now the thrust Q will have aninclined orientation, the whole system being still able inherentstability fully insured as previously, but only with a horizontalcomponent of the thrust Q longitudinally. Itis this longitudinalcomponent which will produce the forward motion of the helicopter, onlysmall inclinations of the thrust-being required and not exceeding ten totwelve degrees at the most relative to the. vertical to give highforward speeds of the helicopter even exceeding the speed of aeroplanes.

65 The distance of the staticai axis C from the 70 the dynamical center0 because for a given set- 75 from the average value) a special positionof ting of Q the. moment of Q in relation to 0 does notechange, butthemoment of 111 does change when the system rolls on longitudinalrails. Thus for every inclination of Q (for values of Q differ motion..With the high-center suspension, this tate around a low axis, such at Cin Fig-14.

to freely oscillate as previouslympon the rolling rails and thihihe forthe inclined position of the thrust 'Q, can also be brought aboutbyother mechanisms requiring a somewhat greater length of the rollingrails.

, For example, the guiding rails 42', 43 may bemade straightcorresponding to location of the statical axis at infinity. Then afterthe displacement of Q parallel to on the longitudinal ra s until themoment of 91 in relation to the dynamical center 0 balances themoment ofQ. The whole system will thus find a position of equilibrium asindicated in] Fig. 13. The position oi the engine set S before on thelongitudinal rails will autoif there will be a rolling and after thethrust Q was shifted to itsoifcenter position is correspondinglyrepresented in.

dot and dash lines.

The engine sets may also be mounted to ro- The displacement of theengine set S around this axis C may be eflected'by a rod 41 articulatedat 46 with the pivoted table 45 carrying the engine cal center willimmediately roll the systemupon the rolling rails and the finalestablished balance will find the thrust Q inclined iorward. A simplecalculation will show that the angle of rolling is approximately equalto twice the angle of adlusting or tilting of the thrust Q. The full'lines' in Fig. -14 represent the final balance of the system upon therolling rails. Around this position the inherent stability bothlongitudinal and lateral is fully insured as previously explained.

The'tilting around the axis C and the locking of the system under anygiven angle can be achieved by any appropriate mechanical means or canbe achieved by an electric servo-motor. In the arrangement shown in Fig.14 the tilting of Q can be controlled from mechanism as schemati-' callyoutlined in Fig. 15, it being understood that the arrangement of Fig. 14requires very little effort to tilt the thrust Q because it involvesonly a "small up and down displacement of the center a l In this tiltingmechanism as shown in Fig. 15

the slide ll mounted on the rod l9 is controlled by connection toopposite ends of the continuous cable running from the upper end of theslide around the pulley 62, then around the pulley ii at the lower-endof the rod 49 and then around the pulley 58 at the other end of thehorizontal rod 60 and then around the control wheel .of the pilotcontrol and back around another pulley, duplicate of 53, and anotherpulley, duplicate of 52, and thenback to the lower end of the slide 48.

At the area ofcontact with the control wheel 55,-

the cable is preferably provided with a chain portion. The control wheel5 5-is operatedby the pilot hand wheel 51 and turns around an axis atthe top of the rod 6|, pivoted by a floating universal joint 54 to therod 60, which in turn is pivoted by an-' lateral, of the engine set 8upon its rails. when,

this engineset oscillates the rod 6| oscillates back and forth, the rod60 oscillating on its two floating universal joints 54 and 52,.rod 49following oscillation of engine set S. The wheels 55, 51 move verylittle and remain well within control of the hands of the pilot, and thehandling of this double wheel by the pilot will have very little effectupon the inherent oscillations of the engine set S because of the almostcomplete absence of any leverage at the wheel.- The lockingarrangementfor the adjustment may be at the hand of the pilot connecting with thewheels 55, 51 or be at the slide 48 and arranged to be automaticallyreleased as soon as either end of the cable 50 is put under tension.

When the thrust Q is first tilted forward by pulling on the cable 50,this will give rise to a horizontal component of Q directed backwards asthe system finds its balance. Such action in the helicopter when movingforward will constitute a breaking of the forwardmovement and can bebrought about by the pilot in flight and will constitute a powerfulmeans for decelerating the forward motion of the helicopter, at landing,for instance, or even in full flight, when required. This is a veryimportant property of the above described high center suspension usedtogether with the thrust tilting.

Whenever the thrust Q is tilted a horizontal component of the tilting isdeveloped. As all the moments of the forces applied to the engine setmust balance in relation to the dynamical center around which this setfreely oscillates, these forces at/ the dynamical center 0 will reducethemselves to a vertical component (Q-p1). =12: (the weight of the bodyand a horizontal component Q1, see Fig. 14) and a horizontal componentequal to the drag of the helicopter body {1 this force Q1 being appliedat the high center 0 to the body will tend to tilt the helicopter body,but this last tilting can be easily overcome by providing the helicopterbody with a horizontal tail plane 15 or a horizontal fin, as shown inFigs. 1, 2, 3, 4, 5, 11 and 16. Now as the drag of the helicopter bodyequal to the thrust component Q1 is proportional to the square of theflying speed and as the air pressure upon the horizontal fin I is alsoproportional to the square of this same speed, then if the tail plane I5will overcome the titlting effect of Q1 for one flying speed, it willovercome this tilting effect for all flying speeds. The conclusion istherefore arrived at that in this helicopter the tail plane does notneed to be an elevator. If when operating the. throttle of the engineslight changes of the incidence of the tail plane are required, thiswill be automatically supplied by slight tiltingofthe helicopter bodyitself Thus in a helicopter rendered inherently stable by the highcenter suspension and the forward motion produced by tilting the thrustQ attained in term by creating a moment of Q in relation to,

the dynamical center 0, the tilting component Q1 of Q may be balanced bya fixed tail plane, such as". located outside the slip stream of the airscrews.

To insure a straight trajectory of the helicopter in flight and toprovide for its turning left and right in motion or in hovering,vertical fins 65, B6 are provided located inside the air screw slipsteam. Such vertical fins 65, 66' can be hinged around horizontal axes61, 68 parallel to the plane of symmetry of the body (Fig. 17) and theirmovements left and right inside the slip stream, with a one sided or twosided action, can be obtained by connecting cables 69, and reels H, 12.Or as shownin Fig. 18 the fins 65'. 66' may be rigidly held at the topand made flexible so that a turning action is secured by their bending.

In Fig. 19 the adjusting means for the table 16 is automaticallyself-locking so as not to require any separate locking and unlockingmechanism or movement. Here. this table 16 is mounted at the end of therod 11 pivoted around the center C" of the carriage 4|". The adjustingcable 50' has its two ends connected to the opposite ends.

of a chain 85 extending around rollers 18 pivoted upon the center C" andthis chain 85 loops around the chain. wheel 19 of the spool 80 passingthrough the slot 8| of the table 16 and having flanges loosely engagingthe upper and lower surfaces of said table. The spool 80 is threaded onthe screw 82 pivoted at 83 on the carriage 4|, and as thechain is pulledone way or the other by the cable 50' the chain wheel 19 turns the spool80 to tip the table 16. A floating rod with two universals at both endsconnects rod 11 to a wheel operated by pilot as in Fig. 15.

I claim;

1. A helicopter comprising an upper lifting unit and a lower loadcarrying u t and means for .supporting said units relatively movablearound a center of suspension above the center of gravity of each so asto secure inherent stability both longitudinally and laterally, saidmeans consisting of relatively sliding parts curved about the center ofsuspension as a center to provide relative motion both longitudinallyand laterally and normally free to move in said directions.

2. A helicopter as set forth in claim 1 in which the center of relativeoscillation between the units is above the highest point of. the upperunit.

3. A helicopter comprising a lifting unit and a load carrying unitrelatively oscillatable around a center of suspension above the centerof gravity of each and means for tilting the air screw thrust in theplane of symmetry by creating a moment of this thrust in relation tosaid center of suspension which moment maintains the thrust in itsinclined position.

4. A helicopter as set forth in claim 3 in which the lifting unit ispivoted to an intermediate carriage having with relation to the loadcarrying unit a universal adjustment longitudinally and laterallyspherical around the center of suspension.

5. A helicopter as set forth in claim 3 in which one part of the liftingunit is pivoted to oscillate longitudinally with relation to the otherpart of. the lifting unit and means is provided on the load carryingunit connected to the lifting unit to control the direction and amountof pivoting between the parts thereof.

6. A helicopter as set forth in claim l'ln which the lifting unit andthe load carrying unit are connected by a track and roller system inwhich the tracks are at right angles to each other and the rails, of thetracks are curved circularly around the center of suspension as acenter.

GEORGE DI: BOTHEZA'I.

